--- //depot/projects/smpng/sys/nfsclient/nfs_vnops.c	2008/08/25 16:33:41
+++ //depot/user/jhb/msi/nfsclient/nfs_vnops.c	2008/09/16 19:41:13
@@ -869,7 +869,8 @@
 		*vpp = NULLVP;
 		return (error);
 	}
-	if ((error = cache_lookup(dvp, vpp, cnp)) && error != ENOENT) {
+	error = cache_lookup(dvp, vpp, cnp);
+	if (error == -1) {
 		struct vattr vattr;
 
 		newvp = *vpp;
@@ -887,6 +888,23 @@
 		else 
 			vrele(newvp);
 		*vpp = NULLVP;
+	} else if (error == ENOENT) {
+		struct vattr vattr;
+
+		/*
+		 * If the parent directory's change time has not
+		 * changed since it was added to the name cache, then
+		 * trust the negative cache entry.  If the parent
+		 * directory has changed, then purge all entries
+		 * associated with it in the name cache.
+		 */
+		if (VOP_GETATTR(dvp, &vattr, cnp->cn_cred, td) == 0 &&
+		    vattr.va_ctime.tv_sec == VTONFS(dvp)->n_ctime) {
+			/* XXX: New stat? */
+			nfsstats.lookupcache_hits++;
+			return (ENOENT);
+		}
+		cache_purge(dvp);
 	}
 	error = 0;
 	newvp = NULLVP;